Both Marvel and DC have had to deal with leaked trailers recently, but one of them definitely responded better than the other.
These above images from from Heath Williams on Twitter and they perfectly illustrate the different approaches in response that Marvel and DC had when trailers leak. Marvel made one of the greatest Tweets ever, while DC basically called some fans at SDCC criminals and cried like a little baby.
To be fair, Marvel did go after Google to find out the identity of the Age of Ultron leaker, but they did it quietly to not drag fans through the mud. DC could learn something from that.